# define  _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int bin_search(int arr[], int left, int right, int key)
{
	while (left <= right) {
		int mid = (left + right) / 2;
		if (arr[mid]<key) {
			left = mid + 1;
		}
		else if (arr[mid] == key) {
			return mid;
		}
		else
		{
			right = mid - 1;
		}
	}
	return -1;
}
int main() {
	int arr[] = { 1,2,3,4,5,6,7,8,9,10 };
	int len = sizeof(arr) / sizeof(arr[0]);
	int ret = bin_search(arr, 0, len - 1, 8);
	printf("%d\n", ret);
	return 0;

}
